The present invention relates to a metal heat storage apparatus used to store heat transmitted from the outside, and in particular, the present invention aims to provide a metal heat storage apparatus which stores, at a high temperature, high-temperature solar energy collected by means of a solar concentrator and such others, and allows a gradual discharge thereof, thereby significantly improving the storage of solar energy, i.e., natural energy.
A solar heat boiler obtains high-temperature solar energy by concentrating solar heat through use of a solar concentrator, and then stores and uses the obtained solar energy.
In general, the heat storage in the solar heat boiler is achieved by various methods. A solar hot water boiler disclosed in the publication of Korean Utility Application No. 20-1999-0036697 (Sep. 27, 1999) is provided as a representative example of the heat storage in the solar heat boiler. The configuration of the above solar hot water boiler is as follows. In the boiler including an electric heater installed therein, a reservoir which holds water is disposed within an outer case. A thermal insulation wall is formed by filling a thermal insulating material between the outer case and the reservoir. A water tube for supplying water is connected to one side of the lower portion of the reservoir. A collecting tube for collecting hot water which has circulated through each heating space is connected to the other side of the lower portion of the reservoir. A circulation pump which forcibly circulates the hot water is installed on the collecting tube. A water outlet tube for supplying water to each heating space requiring heating is connected to one side of the upper portion of the reservoir, so that one hot water tank is constituted. Further, the light collector is provided, which has the following structure. A lens which is installed in such a manner as to rotate with the axis of both frames on the outside of the building and collects solar heat. A solar tracking sensor is installed on one side of the lens. A driving motor which is interworked with the solar tracking sensor and rotates the lens in accordance with the angle of the sun is connected to one end of the rotational axis. A heat collecting plate including a heating tube therein is connected to the lens at the focus position of the lens by a support bar. Both ends of the heating tube and the upper and lower portions of the reservoir are connected with the circular tube. The circular tube which supplies the heated hot water to the reservoir is connected to the upper portion of the reservoir. The circular tube which transfers the hot water to be heated to the heat collecting plate is installed on the lower portion of the reservoir.
In the solar hot water boiler configured as such, after water is heated by the solar heat through the light collector, the hot water is stored in the reservoir surrounded by an insulating layer having an excellent heat insulating efficiency, and then is used as heating water and hot water, and particularly, the hot water is accumulated in the daytime and is used as the heating water at night. However, there are problems. For example, due to a low heat accumulation rate by directly heating the water, the hot water cannot be used for a long period of time. Therefore, the solar hot water boiler configured as such is difficult to actually use in winter and could not be practicalized.
A heat storage tank construction of the solar heat boiler disclosed in Registered Utility Model Publication No. (Y1) 20-0438245 (Feb. 1, 2008) has been provided as another example of the heat storage in the solar heat boiler. The heat storage tank construction of the solar heat boiler includes a heater which is installed to heat the heating water inside the heat storage tank body frame by using the heat transfer medium of the solar heat collector, and a heat exchanger for heating and supplying hot water, which is disposed on the inner upper portion of the body frame in such as to exchange heat with the water heated by the heater. The heater includes the first heating unit and the second heating unit. The first heating unit heats the heating water by winding the coiled tube around the heat exchanger disposed on the inner upper portion of the body frame. The second heating unit heats the heating water by winding the coiled tube around the inner lower portion of the body frame.
Through such a configuration, the heat transfer medium is heated by solar heat and then water is heated by using the heat transfer medium. The configuration has the advantages of obtaining higher heat accumulation rate than that of a method of simply heating the water. However, the volume of the heat storage tank is increased and the functionality is lost when cloudy weather continues.